The oxygen-controlled storage of animal feeds in sealed silos requires that the silage be unloaded from the bottom of the silo. Generally, bottom silo unloaders have a sweep member which rotates about the vertical axis of the silo to move stored material to a center discharge opening through which it drops into another conveyor means that is either in or beneath the floor, that carries the material to the exterior of the silo. The material discharge opening from the discharge conveyor means is provided with a sealed closure.
When a silo is used for the storage of relatively fine, granular material such as shelled corn, the material handling problems are very different from those which exist in the handling of materials such as chopped corn silage and haylage; and as a result the apparatus for discharging grain requires different characteristics from what is needed in an apparatus to discharge chopped corn silage or haylage. Most of the commercial grain unloaders now on the market for use with shelled corn depend upon gravity to unload the grain until it reaches its angle of repose, after which a sweep arm is made operative to remove the remaining grain. Because of this, there are limitations on the maximum moisture content and minimum particle size to insure free flow of the material. The moisture maximum is about 30 percent, and the shelled corn must have been very carefully handled so as to have very few broken kernels. If these requirements are not met, the material may become non-free-flowing, which makes it difficult to remove the material from the silo.
There is a definite need for a mechanically simple, rugged bottom silo unloader which can be readily serviced and maintained by a farmer, and which is capable of handling shelled corn of high moisture content or shelled corn which has been cracked or split, whether such cracked or split corn is of a low or high moisture content.